1. Field of the Invention
The present invention relates to a disc drive that is most suitably used as a thin, small-size optical disc drive, for example. In particular, the invention relates to a technique of inserting and removing a disc-shaped recording medium into and from a drive main body by means of a disc transport member such as a drawer or a tray.
2. Description of the Related Art
Conventionally, in thin, small-size optical disc drives that drive an optical disc such as a CD-ROM and are mounted in notebook-sized personal computers etc., the mainstream type is such that an optical disc is inserted into and removed from a drive main body by means of a drawer or a tray. As shown in FIGS. 1(A)-1(C), an optical disc drive of this type that has been design-registered (IBM Corp.) is such that the width W4 of a drawer main body 6a that is mounted with a spindle motor having a self-chucking-type disc table is made smaller than the diameter D of an optical disc, so that the drawer occupies a smaller space when drawn out of the drive main body and the drive main body can be made smaller.
However, in the optical disc drive in which the width W4 of the drawer is made smaller than the diameter D of an optical disc, if the optical disc 2 is inclined inadvertently as shown in FIG. 1(A) in an attempt of mounting an optical disc 2 on a disc table 12 according to a self-chucking method, the data recording surface 2a of the optical disc 2 may hit the edge 6h of the drawer main body 6a on the optical disc projection side and may be scratched easily or damaged due to impact. Even when the optical disc 2 is mounted on the disc table 12 levelly, if the mounting force is so strong that the outer circumference 2b of the optical disc 2 is bent down as shown in FIG. 1(B), the data recording surface 2a of the optical disc 2 may also hit the edge 6h of the drawer main body 6a on the optical disc projection side and may be scratch easily or damaged due to impact. Further, when the optical disc 2 is removed from the disc table 12, if the optical disc 2 is inclined inadvertently as shown in FIG. 1(C), the data recording surface 2a of the optical disc 2 may also hit the edge 6h of the drawer main body 6a on the optical disc projection side and may be scratched easily or damaged due to impact. In such a case, the reliability of data is extremely lowered.
In the above type of thin, small-size optical disc drives, almost no countermeasures against scratching and damaging of an optical disc 2 have been taken; almost only one measure taken is that the edge 6h of the drawer main body 6a is rounded.
On the other hand, if optical discs 2 are made thinner in the future, the gap between the optical disc 2 that is self-chucked on the disc table 12 and the edge 6h of the drawer main body 6a will become narrower and the chucking force of the self-chucking mechanisms of the disc table 12 will become stronger. This means that the optical disc 2 will become more prone to hit the edge 6h of the drawer main body 6a in mounting or removing the optical disc 2 and hence the data recording surface 2a of the optical disc 2 will become more prone to be scratched or damaged due to impact. Therefore, also for the purpose of protecting the property of users, it is important to take a measure against scratching and damaging of the data recording surface 2a of the optical disc 2.
Incidentally, optical disc drives are mounted with an optical pickup that records and/or reproduces data onto and/or from an optical disc by using a laser beam that is emitted through an objective lens while the objective lens is moved by a carriage between the innermost and outermost tracks of an optical disc. The carriage is moved by a lead screw that is rotationally driven by a motor.
Optical disc drives that drive an optical disc such as a CD-ROM and are mounted in notebook-sized personal computers etc. have been made thinner and smaller year after year. And to save the spaces occupied by parts, the current mainstream design of a carriage transport mechanism is such that the lead screw also serves as a guide main shaft of the carriage transport mechanism, so that no dedicated guide main shaft is necessary.
In conventional carriage transport mechanisms, three to four blocks of mechanism parts are formed by a lead screw that also serves as a guide main shaft, a pair of bearings for supporting both ends of the lead screw, a thrust pressurizing spring for pressing one end of the lead screw in the axial direction and elastically pressing the other end to a thrust receiving member, a motor and a transmission system for rotationally driving the lead screw, and other parts, and those three to four blocks of mechanism parts are attached to the base chassis of an optical pickup on a manufacturing line.
However, the conventional method of attaching three to four blocks of mechanism parts to the base chassis of an optical pickup on a manufacturing line has problems that it requires many assembling steps and is low in productivity because a step of adjusting the loads among the parts and other steps need to be conducted for each block in the final assembling step. Further, this method is low in reliability as exemplified by the facts that considerable dispersion may occur among the loads of the parts and the carriage feed load tends to be rendered unstable. Still further, in order to, for example, replace the optical pickup, it is necessary to disassemble the entire carriage transport mechanism. Therefore, the replacement or the like of the optical pickup is very cumbersome.
In drawer-type optical disc drives, the user tends to inadvertently touch, for example, the carriage of the optical pickup that is mounted on the drawer with his hand in, for example, mounting or removing an optical disc.
On the other hand, the recording density is increasing year after year in those disc drives. In particular, in the CD-R, CD-RW, DVD-RW, etc. that are data-writable, as signals on the disc formats increase in density, signals on the formats will become weaker.
Therefore, there is a problem that if static electricity comes into the carriage when, for example, the user who is charged with static electricity directly touch, for example, the carriage of the optical pickup with his hand, signals that are faint on the format are prone to be destroyed.
The present invention has been made to solve the above problems, and an object of the invention is therefore to prevent the data recording surface of a disc-shaped recording medium from being scratched or damaged when the disc-shaped recording medium is mounted or removed in a disc drive in which the disc mounting width of a disc transport member is smaller than the diameter of the disc-shaped recording medium.
Another object of the invention is to provide a disc drive which can eliminate a step of adjusting the loads among the parts in the final assembling step on a manufacturing line of the entire carriage transport mechanism.
A further object of the invention is to provide a disc drive in which a measure is taken against static electricity that comes into a carriage or some other member without increasing the number of parts or the number of assembling steps.
To attain the above objects, the invention provides a disc drive comprising a disc transport member the width of which for mounting of a disc is smaller than the diameter of the disc and which is inserted into and removed from a drive main body while being mounted with the disc; and a disc protection member provided, so as to face the disc, on an edge of the disc transport member or a region close thereto on a side where the disc that is mounted on the disc transport member projects.
In the above-configured disc drive according to the invention, even if the disc is inadvertently rendered in a state that its recording surface would otherwise hit the edge on the disc projection side in an attempt of mounting or removing the disc, the recording surface actually contacts the disc protection member. This prevents the recording surface from directly hitting the edge of the disc transport member.
According to another aspect of the invention, there is provided a disc drive in which at least a lead screw for moving a carriage and a motor and a transmission system for driving the lead screw are incorporated in a one-piece unit base. With this configuration, the entire carriage transport mechanism can be rendered a unit.
According to a further aspect of the invention, there is provided a disc drive comprising a carriage that is mounted with an optical pickup for recording or reproducing a signal onto or from a disc, a lead screw elastically for moving the carriage, and a spring member for pressing the lead screw against a thrust receiving member, wherein the spring member effects grounding between the carriage, a unit chassis, and a drive main body.
In the above disc drive according to the invention, since the carriage can be grounded by the spring member that presses the lead screw, even if static electricity enters the carriage or some other member when, for example, the user touches it with his hand, the static electricity can safely be led to the ground.